The Arctic, which is the subject of Sara Wheeler's smashing new book, "The Magnetic North," has been many things: a homeland for hunter-gatherers, a stomping ground for trappers, an object of me-first exploration, a jail for political dissidents, a sentry post in the Cold War, a sinkhole for pollution and a site of mineral extraction. Deploying an inquisitive mind and a crisp, witty prose style, Wheeler takes the reader on an informative and ultimately tragic tour of a region in the throes of drastic change.

"The Magnetic North" proceeds in a geographical circle, from the Russian Arctic to Alaska and Canada, to Greenland and Scandinavia, and back to Russia at the end. As Wheeler fills in background on the places she visits, American and British readers may encounter some familiar episodes. Among these is the 19th-century hunt for a Northwest Passage by the inept Sir John Franklin, whose expedition came to a gruesome end when starving participants took to eating the corpses of colleagues who preceded them in death. Wheeler makes the story fresh, however, by emphasizing the reaction of Charles Dickens back home. The most influential writer in England simply willed out of existence the Inuits' testimony about what they had found at the explorers' last camp on King William Island in Canada: kettles holding human cutlets. The exploring party couldn't have been cannibals, Dickens decreed in a magazine article. "The noble conduct and example of such men . . . outweighs by the weight of the whole universe the chatter of a gross handful of uncivilized people, with a domesticity of blood and blubber."

Also well-known is the story of how indigenous people were converted by Christian missionaries, educated to read and write (though not in their own language), and discouraged from mastering the outdoors skills that had allowed their forebears to survive for millennia in one of the world's most demanding environments. Wheeler's account makes clear that the same disastrous severing occurred throughout the Arctic. Her critique of Canada's policies could just as easily apply to Russia, the United States, Sweden - every nation that has asserted jurisdiction over the Far North: "I began to understand that wherever the state intervened in the . . . Arctic, which was almost everywhere, the mechanics of the system moved in an arbitrary, aimless fashion, like the hands of a clock disconnected from the machinery behind the face."

Other places and sagas in the book will be new to most Westerners - such as the survival of a monastery on an island in Russia's White Sea. The institution withstood Stalin's Terror in the 1920s and '30s, and the revival it has enjoyed since the fall of communism elicits one of Wheeler's rare outbursts of optimism. In the monks' staying power, she saw "a humanity that eluded articulation, and I had sensed it everywhere in the muddled and lovable Arctic."

Wherever she goes, Wheeler exhibits a knack for summing up people, places and things memorably. She describes Rockwell Kent, the American painter and illustrator who fell in love with the Far North, as Greenland's Gauguin, "who saw his Tahiti in the starlit winters of Igdlorssuit." She corrects those who assume that scenery without trees, mountains or valleys must be dull: "The interior of an ice sheet is the most mesmerizing of all polar landscapes." She evokes the futile battle against insects: "The pages of my notebook tell their own story, encrusted with flattened mosquito and blackfly corpses and splotches of my own blood. The bugs bit us even as we wore jackets with full-head net hoods and peered out at the landscape through a veil of brown mesh."

Only once did I part company with her. Changing planes in Pond Inlet, at the north end of Baffin Island, she dismisses the village as "bleak." But with its outlook on a bay and beyond that Bylot Island, which is dominated by a sinuous glacier, Pond Inlet is one of the world's most beautiful places. How Wheeler could have missed this is a puzzlement.

"The Magnetic North" gives ample coverage to the damage being done to the Arctic by pollution and global warming, but for an account of the effects on a specific creature, readers should turn to Kieran Mulvaney's illuminating "The Great White Bear." Mulvaney has ventured far from his home in Alexandria, Va., to watch polar bears, notably in northern Alaska and on Hudson Bay. He tells unsettling tales of human-bear encounters, including one that the great Norwegian explorer Roald Amundsen survived only because his dog got involved. That anecdote ends with Amundsen relating his surprising thoughts during what he feared might be his last seconds of life: "I lay there wondering how many hairpins were swept up on the sidewalks of Regent Street in London on a Monday morning!"

Polar bears are imperiled because they use ice floes as platforms from which to hunt seals and on which to haul up and rest - and not only is Arctic ice disappearing at a fearsome rate, but it's hard to see what could reverse that trend. As a result, polar bears may be reduced to relict populations in the High Arctic and Greenland by the middle of this century. Beyond that, one hardly dares look.